The Mexican National Middleweight Championship (Campeonato National Medio in Spanish) was a national Mexicanprofessional wrestlingchampionship controlled by a "National title" controlled by the "Comisión de Box y Lucha Libre Mexico D.F." (Mexico City Boxing and Wrestling Commission), which regulates all matches where the title is defended. The title has been in use since at least 1933 until December 8, 2008. It was defended in the Asistencia Asesoría y Administración (AAA) promotion since AAA's inception in 1992. Since it is a National title endorsed by the Comisión it could technically be defended in various Mexican promotions, but in reality was promoted mainly by AAA from 1992 until 2008.

The Championship dates back to 1933, making it one of the oldest professional wrestling champions still in use today predating all active titles in both North America and Japan. Records of how the first champion, Yaqui Joe, are unclear due to minimal written documentation from that period. No documentation exists that the championship was created for Empresa Mexicana de Lucha Libre (EMLL, later renamed CMLL) but during the 1930s and '40s the promotion was granted control of the title by the Comisión.[Note 1] In 1992 Antonio Peña founded Asistencia Asesoría y Administración taking a number of CMLL wrestlers with him. One of these wrestlers was the then reigning National Middleweight Champion Octagón who took the championship with him. When Blue Panther won the championship in on July 27, 1992 it was officially acknowledged by the Commission that AAA controlled the booking of the championship from that point forward.

Octagón was the most recent Mexican National Middleweight Champion. His last reign was his fourth title reign and the 60th overall champion. Octagón was also the 45th, 57th and 51st champion.[1] The status of Octagón's title reign is unclear after AAA announced that they would not publicly recognize any titles without the AAA name.[2]El Santo and Octagón are tied for the most reigns with four each. El Santo has held the title for the most days, accumulating 4 reigns that add up to a minimum of 3256 days in total. Perro Aguayo has held the title the shortest length of time with 11 days.

The title is a "National" title which means that non-Mexican citizens are prohibited from challenging or holding the championship. The official definition of the middleweight weight class in Mexico is between 82 kg (181 lb) and 87 kg (192 lb), but is not always strictly enforced.[Note 2][3] Being a professional wrestling championship, it is not won legitimately; it is instead won via a scripted ending to a match or awarded to a wrestler because of a storyline.

The championship is generally not allowed to be defended in any other type of match than a regular match, as is the case for all the Mexican National titles. The commission has been inconsistent on enforcing the rules, in one case they stripped Psicosis II of the championship for defending it in a hardcore match, in another case they allowed the Mexican National Heavyweight Championship to change hands in a Steel cage match.[4]